the community site for and by developmental biologists

Rethinking X-chromosome Inactivation

Posted by on April 30th, 2011

I’ve been asked to present the back-story behind our recently published manuscript in Development “Transcription precedes loss of Xist coating and depletion of H3K27me3 during X-chromosome reprogramming in the mouse inner cell mass.” Mammalian dosage compensation occurs by silencing one X-chromosome in female cells, termed X-chromosome Inactivation (XCI).  Balancing X-linked gene transcription is critical for[…]

Stem cell patent case could have far-reaching impact

Posted by on April 28th, 2011

Last month, the advocate-general of the European Court of Justice gave his opinion on a long-running legal debate about a patent filed several years ago in Germany. If the Court follows his recommendation, patenting of applications using embryonic stem cells will be prohibited on moral grounds. 13 leaders of major stem cell projects in Europe responded to[…]

Got the Blues? How Plants Respond to Blue Light

Posted by on April 28th, 2011

Physiologically speaking of course….

As humans we can see a limited assortment of light wavelengths, known as the visible spectrum of light, a.k.a. colours. (Other wavelengths we cannot see include UV rays, X rays or infrared). Why is it that we can differentiate colours? Its likely to do with adaptation to the environment. Plants and animals have evolved different physiological responses to colours, so it’s important to discriminate between them.

As mammals we have biological clocks, or circadian rhythms that respond to light. Dark or blue light set off signalling mechanisms, which ultimately regulate the melatonin levels in our system. Melatonin is a hormone which can induce sleep, if at sufficiently high levels in our system. (Hence your doctor prescribing you melatonin if you have trouble sleeping at night. Suffice to say countless grad students are probably on this stuff right now).

Plants also have a light-sensing system, which can respond to different times of day and seasonal changes. This can determine fruit maturation and changing colour in the leaves etc. For plants, blue light has a revitalizing (instead of drowsy) effect. If you’ve ever left your plants without light for too long, they go yellow. Irradiate them with a little blue, and the green will return within a couple of days.

Interestingly, plants and animals have the same type of photoreceptors to blue light, called Cryptochromes (CRYs), even though they elicit a different response. CRYs initiate the light response, analogous to a molecular domino effect. The pigments bind specialized proteins that in turn, regulate transcription factors that can switch on the light response genes involved in development. Termed as photomorphogenesis, light dependent changes in development can include initiation of flowering, or extension of roots in germinating seeds.

Currently, characterizing the molecular interactions in plant blue-light/CRY1 response seems to be a hot topic. Two highly similar articles were just published in Genes & Development, which was drawn to my attention by Eva (cheers). They were produced by two different research crews, using virtually the same methods to similar results. It’s not by total coincidence either. Characterizing molecular interactions in plants involve the same gold standard biochemical and genetic assays (i.e. transgenic plants, yeast hybrid systems, loss-of-function mutants etc.)

(Photoreceptors = light absorbing molecules or pigments.)

Location change for BSDB Node meet-up

Posted by on April 28th, 2011

We’ve had to find a new location for Thursday’s (today’s) Node meetup at the BSDB meeting. Find us Thursday April 28 at 8PM in the Gulbenkian Cinema Cafe/Bar. This is the cafe with the big windows that you pass when you follow the footpath from Eliot Dining Hall to the Woolf College building. This happens[…]

Postdoctoral positions at the University of Pennsylvania

Posted by on April 27th, 2011

Two postdoctoral positions are available immediately at the University of Pennsylvania: (1) to analyze the gene regulatory network underlying neural crest formation (Hong & Saint-Jeannet, 2007. Mol Biol Cell 18, 2192-2202; Hong et al., 2008. Development 135, 3903-3910); and (2) to characterize the molecular regulators of cardiac neural crest migration (Lee & Saint-Jeannet, 2011. Development[…]

Mapping the cardiac neural crest in the frog’s heart

Posted by on April 27th, 2011

The Node’s staff asked me to write a short “behind the scenes” on our paper just released in the May 15 issue of Development, “Cardiac neural crest is dispensable for outflow tract septation in Xenopus” In the summer of 2008 when Dr. Young-Hoon Lee joined my laboratory from Chonbuk National University for a sabbatical[…]

In Development this week (Vol. 138, Issue 10)

Posted by on April 26th, 2011

Here are the research highlights from the current issue of Development: FatJ keeps neural progenitor pools in shape The correct development and functioning of the spinal cord depends on the patterning, proliferation and differentiation of neural progenitor cell cohorts along the dorsoventral axis of the neural tube. But how are the numbers of these cells[…]

Schwann cells and N-WASp: it always comes down to actin

Posted by on April 22nd, 2011

Axons have such important jobs to do that they require their own support staff.  Schwann cells are responsible for ensheathing axons of the peripheral nervous system with myelin, which allows rapid conduction of action potentials.  The process by which Schwann cells do this was understood to involve cytoskeletal regulators, and a recent paper in Development[…]

Select a Development cover – round 2

Posted by on April 21st, 2011

A few weeks ago, you selected this sea urchin image from the Woods Hole embryology course as a cover for Development. We have many more images from this course, and more opportunities to choose a journal cover. Here is the second batch. Which of these images would you like to see on the cover of[…]

Travel fellowships deadline approaching

Posted by on April 21st, 2011

The next deadline for Development’s travelling fellowships is coming up on April 30, and Development would like to encourage you to apply if you are a graduate student or postdoc planning to work for a few months in a distant lab. Have a look at the fellowship site for the full requirements, and read these[…]